The present invention relates to electrodes for electrolysis, particularly the electrolysis of sodium chloride, said electrodes having a coating of cobalt and titanium compounds.
For the last 20 years or so, metal anodes have been used more and more commonly for the electrolysis of sodium chloride, both in mercury cells and in diaphragm or membrane cells, and both for the production of chlorine and of soda and for the production of oxygen derivatives, such as the chlorates. The anodes used in industry generally comprise a substrate, generally of titanium, covered with metals of the platinum group or their oxides, possibly mixed with oxides of other metals, particularly titanium in rutile form, which oxide is formed furthermore in situ during use of the electrode in electrolysis. The use of precious metals results in large monetary investments in the erection of manufacturing facilities. Furthermore, the consumption of these expensive metals, although low in weight, reaches an amount which is not negligible as compared with the value of the products of the electrolysis. It is, therefore, completely understandable that numerous attempts have been made to replace the metals of the platinum group with compounds of non-precious metals. Among these compounds, cobalt oxide has been mentioned, for instance, in U.S. Pat. Nos. 3,399,966 and 3,977,958. No publication is known concerning the industrial development of such electrodes, which may indicate that they are not providing adequate satisfaction in industrial production, in particular, of chlorine. Other recent patents which have issued to our assignee are U.S. Pat. Nos. 3,917,525; 4,010,091; and 4,115,239.
It has now been found that it is possible to produce electrodes employing no precious metals, but employing only readily obtained compounds of moderate price in coatings which have an excellent life when employed in the electrolysis of alkali chlorides.
It is, accordingly, an object of the present invention to provide novel and effective electrodes for the electrolysis of alkali chlorides which do not require the use of the precious metals.
It is a further object of the invention to provide useful and effective electrodes for electrolytic cells which employ only relatively inexpensive metals.
Other objects of the invention will be apparent to those skilled in the art from the present disclosure.